Ultrahuman Ring AIR-Smart Ring Activity Tracker, Size First with Ultrahuman Sizing Kit,Sleep Tracker,Smart Ring for Men/Women,Fitness Tracker (Size 8)Buy the Sizing Kit First: Ultrahuman Ring sizes differ from standard ring sizes. Purchase the Ultrahuman Sizing Kit first, which includes a ring sizer, to accurately determine your size. The Ring AIR is available in 10 sizes (5 14), ensuring a comfortable, secure fit. Using the sizing kit helps you avoid returns and exchanges, ensuring you select the right size before purchasing. Comprehensive Health Tracking: The Ultrahuman Ring measures a wide range